System and method to increase surface tension and contact angle in immersion lithography

ABSTRACT

A system and method to allow organic fluids to be used in immersion lithographic systems. This is done by providing a showerhead portion of a liquid supply system that is partially coated or made from a TEFLON like material. The TEFLON like material reduces wetness effect, and thus increases containment, when using an organic immersion fluid in a space between the last optic and the substrate.

BACKGROUND

1. Field

The present invention relates to a lithographic apparatus and a methodfor manufacturing a device.

2. Background

A lithographic apparatus is a machine that applies a desired patternonto a substrate, usually onto a target portion of the substrate. Alithographic apparatus can be used, for example, in the manufacture ofintegrated circuits (ICs). In that instance, a patterning device, whichis alternatively referred to as a mask, a reticle, an array ofindividually controllable elements, etc. can be used to generate acircuit pattern to be formed on an individual layer of the IC. Thispattern can be transferred onto a target portion (e.g., comprising partof, one, or several dies) on a substrate (e.g., a silicon wafer or aflat panel display substrate). Transfer of the pattern is typically viaimaging onto a layer of radiation-sensitive material (resist) providedon the substrate.

In general, a single substrate will contain a network of adjacent targetportions that are successively patterned. Known lithographic apparatusinclude steppers, in which each target portion is irradiated by exposingan entire pattern onto the target portion at one time, and scanners, inwhich each target portion is irradiated by scanning the pattern througha radiation beam in a given direction (the “scanning”-direction), whilesynchronously scanning the substrate parallel or anti-parallel to thisdirection. It is also possible to transfer the pattern from thepatterning device to the substrate by imprinting the pattern onto thesubstrate.

It has been proposed to immerse the substrate in the lithographicprojection apparatus in a liquid having a relatively high refractiveindex, e.g., water, so as to fill a space between the final element ofthe projection system and the substrate. The point of this is to enableimaging of smaller features since the exposure radiation will have ashorter wavelength in the liquid. The effect of the liquid can also beregarded as allowing the numerical aperture (NA) of the system to behigher than 1 and also increasing the depth of focus. Other immersionliquids have been proposed, including water with solid particles (e.g.,quartz) suspended therein.

However, submersing the substrate or substrate and substrate table in abath of liquid means that there is a large body of liquid that must beaccelerated during a scanning exposure. This requires additional or morepowerful motors and turbulence in the liquid can lead to undesirable andunpredictable effects.

One of the solutions proposed is for a liquid supply system to provideliquid on only a localized area of the substrate and in between thefinal element of the projection system and the substrate (the substrategenerally has a larger surface area than the final element of theprojection system).

A gap between the liquid supply system and the substrate allows theseelements to move with respect to each other. Because of this gap, thereis a need to have high surface tension between the immersion liquid andat least a “showerhead” portion of the liquid supply system to keep theimmersion liquid from flowing through this gap. For example, ashowerhead can be a portion of the liquid supply system that comprisesinlet and outlet ports and/or channels. A problem that can arise inimmersion lithography systems small contact angles between an immersionliquid and a surface of the substrate and the liquid supply system. Thiscan be due to wetness effects of using certain materials for the liquidsupply system and/or the immersion liquid. Small contact angles can leadto low surface tension between the immersion liquid and the showerhead.Thus, the immersion liquid may flow over the entire substrate surface orleak through the gap, which are both highly undesirable.

A still further problem is that certain immersion liquids causecorrosion of the liquid supply system when it is made from steel.Corrosion can contaminate the immersion liquid and cause defects on thesubstrate surface. One way to alleviate this problem is by changing ofthe immersion liquid. However, changing the immersion liquid can lead toother problems, such as wetness problems.

Therefore, what is needed is a system and method that allow for reducedwetness characteristics without causing contamination of the immersionliquids.

SUMMARY

One embodiment of the present invention provide a lithography systemcomprising an illumination system, a patterning device, a projectionsystem, and a liquid supply system. The illumination system conditions abeam of radiation. The patterning device patterns the beam. Theprojection system projects the patterned beam onto a target portion of asubstrate. The liquid supply system at least partially fills a spacebetween the projection system and the substrate with an immersion liquidhaving an index of refraction greater than that of water or 1.10.

In one example, at least a portion of a surface of the liquid supplysystem is coated with one of PTFE, TFE, a Teflon, and Teflon-likefluorinated hydrocarbon polymer.

In another example, at least a portion of a surface of the liquid supplysystem is made from one of PTFE, TFE, a Teflon, and Teflon-likefluorinated hydrocarbon polymer.

In a further example, the immersion liquid has an index of refractiongreater than about 1.11, for example 1.65 for improved immersionlithography.

Another embodiment of the present invention provides a method. Thismethod comprises projecting a patterned beam of radiation onto a targetportion of a substrate using a projection system and at least partiallyfilling a spaced between the projection system and the substrate with animmersion liquid having an index of refraction greater than that ofwater or 1.10 from the liquid supply system. In one example, theimmersion liquid is supplied using a liquid supply system, at least aportion of which is one of coated with or made from one of PTFE, TFE,TEFLON, and a Teflon-like fluorinated hydrocarbon polymer.

Further embodiments, features, and advantages of the present inventions,as well as the structure and operation of the various embodiments of thepresent invention, are described in detail below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, further serve to explainthe principles of the invention and to enable a person skilled in thepertinent art to make and use the invention.

FIG. 1 depicts a lithographic apparatus according to an embodiment ofthe present invention

FIGS. 2 and 3 depict a liquid supply system for use in a lithographicprojection apparatus.

FIG. 4 depicts another liquid supply system for use in a lithographicprojection apparatus.

FIG. 5 depicts another liquid supply system for use in a lithographicprojection apparatus.

FIG. 6 shows a portion of a liquid supply system for use in alithographic apparatus, according to one embodiment of the presentinvention.

FIGS. 7 and 8 show contact angles of a fluid with respect to the portionof the liquid supply system shown in FIG. 6, according to embodiments ofthe present invention.

FIG. 9 shows a flowchart depicting a method, according to one embodimentof the present invention.

The present invention will now be described with reference to theaccompanying drawings. In the drawings, like reference numbers canindicate identical or functionally similar elements. Additionally, theleft-most digit(s) of a reference number can identify the drawing inwhich the reference number first appears.

DETAILED DESCRIPTION

While specific configurations and arrangements are discussed, it shouldbe understood that this is done for illustrative purposes only. A personskilled in the pertinent art will recognize that other configurationsand arrangements can be used without departing from the spirit and scopeof the present invention. It will be apparent to a person skilled in thepertinent art that this invention can also be employed in a variety ofother applications.

One or more embodiments of the present invention provide a system andmethod that allow organic fluids to be used in immersion lithographicsystems. This is done by providing a showerhead portion of a liquidsupply system that is partially coated or made from a TEFLON likematerial. The TEFLON like material reduces wetness effect, and thusincreases containment, when using an organic immersion fluid in a spacebetween the last optic and the substrate

FIG. 1 schematically depicts a lithographic apparatus according to oneembodiment of the invention. The apparatus comprises an illuminationsystem, a support structure, a substrate table, and a projection system.The illumination system (illuminator) IL conditions a radiation beam PB(e.g., UV radiation or DUV radiation). The support structure (e.g., amask table) MT supports a patterning device (e.g., a mask) MA and isconnected to a first positioner PM configured to accurately position thepatterning device in accordance with certain parameters. The substratetable (e.g., a wafer table) WT holds a substrate (e.g., a resist-coatedwafer or a flat panel substrate) W and connected to a second positionerPW configured to accurately position the substrate in accordance withcertain parameters. The projection system (e.g., a refractive projectionlens system) PL projects a pattern imparted to the radiation beam PB bypatterning device MA onto a target portion C (e.g., comprising one ormore dies) of the substrate W.

The illumination system can include various types of optical components,such as refractive, reflective, magnetic, electromagnetic, electrostaticor other types of optical components, or any combination thereof, fordirecting, shaping, or controlling radiation.

The support structure holds the patterning device in a manner thatdepends on the orientation of the patterning device, the design of thelithographic apparatus, and other conditions, such as for examplewhether or not the patterning device is held in a vacuum environment.The support structure can use mechanical, vacuum, electrostatic, orother clamping techniques to hold the patterning device. The supportstructure can be a frame or a table, for example, which can be fixed ormovable as required. The support structure can ensure that thepatterning device is at a desired position, for example with respect tothe projection system. Any use of the terms “reticle” or “mask” hereincan be considered synonymous with the more general term “patterningdevice.”

The term “patterning device” used herein should be broadly interpretedas referring to any device that can be used to impart a radiation beamwith a pattern in its cross-section such as to create a pattern in atarget portion of the substrate. It should be noted that the patternimparted to the radiation beam may not exactly correspond to the desiredpattern in the target portion of the substrate, for example if thepattern includes phase-shifting features or so called assist features.Generally, the pattern imparted to the radiation beam will correspond toa particular functional layer in a device being created in the targetportion, such as an integrated circuit.

The patterning device can be transmissive or reflective. Examples ofpatterning devices include masks, programmable mirror arrays, andprogrammable LCD panels. Masks are well known in lithography, andinclude mask types such as binary, alternating phase-shift, andattenuated phase-shift, as well as various hybrid mask types. An exampleof a programmable mirror array employs a matrix arrangement of smallmirrors, each of which can be individually tilted so as to reflect anincoming radiation beam in different directions. The tilted mirrorsimpart a pattern in a radiation beam which is reflected by the mirrormatrix.

The term “projection system” used herein should be broadly interpretedas encompassing any type of projection system, including refractive,reflective, catadioptric, magnetic, electromagnetic and electrostaticoptical systems, or any combination thereof, as appropriate for theexposure radiation being used, or for other factors such as the use ofan immersion liquid or the use of a vacuum. Any use of the term“projection lens” herein can be considered as synonymous with the moregeneral term “projection system”.

As here depicted, the apparatus is of a transmissive type (e.g.,employing a transmissive mask). Alternatively, the apparatus can be of areflective type (e.g., employing a programmable mirror array of a typeas referred to above, or employing a reflective mask).

The lithographic apparatus can be of a type having two (dual stage) ormore substrate tables (and/or two or more support structures). In such“multiple stage” machines the additional tables or support structure canbe used in parallel, or preparatory steps can be carried out on one ormore tables or support structures while one or more other tables orsupport structure are being used for exposure.

Referring to FIG. 1, the illuminator IL receives a radiation beam from aradiation source SO. The source and the lithographic apparatus can beseparate entities, for example when the source is an excimer laser. Insuch cases, the source is not considered to form part of thelithographic apparatus and the radiation beam is passed from the sourceSO to the illuminator IL with the aid of a beam delivery system BDcomprising, for example, suitable directing mirrors and/or a beamexpander. In other cases the source can be an integral part of thelithographic apparatus, for example when the source is a mercury lamp.The source SO and the illuminator IL, together with the beam deliverysystem BD if required, can be referred to as a radiation system.

The illuminator IL can comprise an adjuster AD for adjusting the angularintensity distribution of the radiation beam. Generally, at least theouter and/or inner radial extent (commonly referred to as σ-outer andσ-inner, respectively) of the intensity distribution in a pupil plane ofthe illuminator can be adjusted. In addition, the illuminator IL cancomprise various other components, such as an integrator IN and acondenser CO. The illuminator can be used to condition the radiationbeam, to have a desired uniformity and intensity distribution in itscross-section.

The radiation beam PB is incident on the patterning device MA, which isheld on the support structure (e.g., mask table) MT, and is patterned bythe patterning device. Having traversed the patterning device MA, theradiation beam PB passes through the projection system PL, which focusesthe beam onto a target portion C of the substrate W. An immersion hoodIH, which is described further below, supplies immersion liquid to aspace between the final element of the projection system PL and thesubstrate W.

With the aid of the second positioner PW and position sensor IF (e.g.,an interferometric device, linear encoder or capacitive sensor), thesubstrate table WT can be moved accurately, e.g., so as to positiondifferent target portions C in the path of the radiation beam PB.Similarly, the first positioner PM and another position sensor (which isnot explicitly depicted in FIG. 1) can be used to accurately positionthe patterning device MA with respect to the path of the radiation beamPB, e.g., after mechanical retrieval from a mask library, or during ascan. In general, movement of the support structure MT can be realizedwith the aid of a long-stroke module (coarse positioning) and ashort-stroke module (fine positioning), which form part of the firstpositioner PM. Similarly, movement of the substrate table WT can berealized using a long-stroke module and a short-stroke module, whichform part of the second positioner PW.

In the case of a stepper (as opposed to a scanner) the support structureMT can be connected to a short-stroke actuator only, or can be fixed.Patterning device MA and substrate W can be aligned using patterningdevice alignment marks M1, M2 and substrate alignment marks P1, P2.

Although the substrate alignment marks as illustrated occupy dedicatedtarget portions, they can be located in spaces between target portions(these are known as scribe-lane alignment marks). Similarly, insituations in which more than one die is provided on the patterningdevice MA, the patterning device alignment marks can be located betweenthe dies.

The depicted apparatus could be used in at least one of the followingmodes:

1. In step mode, the support structure MT and the substrate table WT arekept essentially stationary, while an entire pattern imparted to theradiation beam is projected onto a target portion C at one time (i.e., asingle static exposure). The substrate table WT is then shifted in the Xand/or Y direction so that a different target portion C can be exposed.In step mode, the maximum size of the exposure field limits the size ofthe target portion C imaged in a single static exposure.

2. In scan mode, the support structure MT and the substrate table WT arescanned synchronously while a pattern imparted to the radiation beam isprojected onto a target portion C (i.e., a single dynamic exposure). Thevelocity and direction of the substrate table WT relative to the supportstructure MT can be determined by the (de-) magnification and imagereversal characteristics of the projection system PL. In scan mode, themaximum size of the exposure field limits the width (in the non-scanningdirection) of the target portion in a single dynamic exposure, whereasthe length of the scanning motion determines the height (in the scanningdirection) of the target portion.

3. In another mode, the support structure MT is kept essentiallystationary holding a programmable patterning device, and the substratetable WT is moved or scanned while a pattern imparted to the radiationbeam is projected onto a target portion C. In this mode, generally apulsed radiation source is employed and the programmable patterningdevice is updated as required after each movement of the substrate tableWT or in between successive radiation pulses during a scan. This mode ofoperation can be readily applied to maskless lithography that utilizesprogrammable patterning device, such as a programmable mirror array of atype as referred to above.

Combinations and/or variations on the above described modes of use orentirely different modes of use can also be employed.

FIGS. 2 and 3 depict a liquid supply system for use in a lithographicprojection apparatus. As illustrated in FIGS. 2 and 3, liquid, shown asa darkened area under projection system PL, is supplied by at least oneinlet IN onto the substrate W along the direction of movement (shown asan arrow) of the substrate W relative to a final element of projectionsystem PL. The liquid is removed by at least one outlet OUT after havingpassed under the projection system PL. That is, as the substrate W isscanned beneath the element in a −X direction, liquid is supplied at the+X side (in this perspective the right side) of the element and taken upat the −X side (in this perspective the left side) of the element.

FIG. 2 shows the arrangement schematically in which liquid is suppliedvia inlet IN and is taken up on the other side of the element by outletOUT, which can be connected to a low pressure source. Although in theillustration of FIG. 2 the liquid is supplied along the direction ofmovement (noted by the arrow) of the substrate W relative to the finalelement of projection system PL, though this does not need to be thecase.

Various orientations and numbers of in- and out-lets positioned aroundthe final element are possible. For example, the arrangement shown inFIG. 3. In this example, four sets of an inlet with an outlet on eitherside are provided in a regular pattern around the final element ofprojection system PL.

FIG. 4 depicts another liquid supply system for use in a lithographicprojection apparatus. In this example, a localized liquid supply systemis shown. Liquid is supplied by two groove inlets IN on either side ofthe projection system PL and is removed by a plurality of discreteoutlets OUT arranged radially outwardly of the inlets IN. The inlets INand outlets OUT can be arranged in a plate with a hole in its center,and through which the projection beam is projected. Liquid is suppliedby one groove inlet IN on one side of the projection system PL andremoved by a plurality of discrete outlets OUT on the other side of theprojection system PL, causing a flow of a thin film of liquid betweenthe projection system PL and the substrate W. The choice of whichcombination of inlet IN and outlets OUT to use can depend on thedirection of movement of the substrate W (the other combination of inletIN and outlets OUT being inactive).

FIG. 5 depicts another liquid supply system for use in a lithographicprojection apparatus. In this example, a lithography device with alocalized liquid supply system solution is to provide the liquid supplysystem with a liquid confinement structure 12 that extends along atleast a part of a boundary of the space between the final element of theprojection system PL and the substrate table WT. The liquid confinementstructure 12 is substantially stationary relative to the projectionsystem PL in the XY plane, though there can be some relative movement inthe Z direction (in the direction of the optical axis). In anembodiment, a seal 16 is formed between the liquid confinement structure12 and the surface of the substrate W.

In one example, reservoir 10 forms a contactless seal to the substrate Waround the image field of the projection system PL so that liquid 11 isconfined to fill a space between the substrate W surface and the finalelement of the projection system PL. The reservoir 10 is formed by aliquid confinement structure 12 positioned below and surrounding thefinal element of the projection system PL. Liquid 11 is brought into thespace below the projection system PL and within the liquid confinementstructure 12. The liquid confinement structure 12 extends a little abovethe final element of the projection system PL and the liquid level risesabove the final element so that a buffer of liquid 11 is provided. Theliquid confinement structure 12 has an inner periphery that at the upperend. In one example, the upper end closely conforms to the shape of theprojection system PL or the final element thereof and can be, e.g.,round. At the bottom, the inner periphery closely conforms to the shapeof the image field, e.g., rectangular, though this need not be the case.

In one example, the liquid 11 is confined in the reservoir 10 by a gasseal 16 between the bottom of the liquid confinement structure 12 andthe surface of the substrate W. The gas seal 16 is formed by gas. Invarious examples, the gas can be air, synthetic air, N₂ or another inertgas, which is provided under pressure via inlet 15 to the gap betweenliquid confinement structure 12 and substrate W and extracted via outlet14. The overpressure on the gas inlet 15, vacuum level on the outlet 14,and geometry of the gap are arranged so that there is a high-velocitygas flow inwards that confines the liquid. Such a system is disclosed inU.S. Pat. No. 6,952,253 that issued Oct. 4, 2005, which is herebyincorporated by reference in its entirety.

In European Patent Application No. 03257072.3, which is incorporated byreference herein in its entirety, the idea of a twin or dual stageimmersion lithography apparatus is disclosed. Such an apparatus isprovided with two tables for supporting a substrate. Levelingmeasurements are carried out with a table at a first position, withoutimmersion liquid, and exposure is carried out with a table at a secondposition, where immersion liquid is present. Alternatively, theapparatus has only one table.

FIG. 6 shows a portion 600 of a liquid supply system for use in alithographic apparatus, according to one embodiment of the presentinvention. Portion 600 applies an immersion fluid 602 between a lastoptic 604 of a projection system PL and a substrate W. Immersion fluid602 at least partially fills a space 606 between last optic 604 andsubstrate W. Immersion fluid 602 flows from a source (not shown) in thedirection of arrow A through inlet 608 into space 606 and flows in thedirection of arrow B through outlet 610 into a receptacle (not shown),for example similarly to as described above. Inlet and outlet 608 and610, respectively, are located within a showerhead portion 612 ofportion 600.

It is too be appreciated that projection system PL and immersion fluid602 are moving with respect to substrate W, for example between about200 mm and 400 mm per second, or more desirable around 300 mm a second.Thus, it is highly desirable to contain immersion fluid 602 during thismovement. In one example, immersion fluid 602 is contained throughsurface tension with respect to a surface 630 of the liquid supplysystem.

In one example, a gas (e.g., nitrogen) also flows into space 606 in thedirection of arrow C through inlet 614 and in the direction of arrow Dthrough inlet 616. For example, the gas can form knife edges 618 in agap 620 between showerhead 612 and substrate W. These knife edges 618can act as a barrier or curtain to also assist in containing immersionfluid 602 and/or to prevent against oxygen entering immersion fluid 602.This can cause contamination and/or increased absorption to shorterwavelengths of light, e.g., in about the 1-300 nanometer range.

In one example, showerhead 612 can be made from a steel material, or thelike. Using steel was satisfactory when water was used as immersionfluid 602. However, in order to increase numerical aperture of the lastoptic 604, different materials can be used for immersion fluid 602 thathave higher indexes of refraction than water, for example organic fluidshaving index of refractions of about up to about 1.65, or above. Thisallows last optic 604 of projection system PL to exhibit higher NAcharacteristics, which increases resolution of a pattered beam to formsmaller and more accurate features on substrate W. In one example,materials such as Decahydronaphthalene (Decalin) can be used, which hasan index of refraction of 1.65. However, when steel is used for theshowerhead 612, undesirable wetting effects have resulted. Small contactangles form between the organic immersion fluids and the showerhead 612and the substrate W, which can overshadow the benefits of using theorganic immersion fluid.

FIG. 7 shows a contact angle between an organic immersion fluid 702,having a higher index of refraction than water, and steel showerhead612, according to one embodiment of the present invention. For example,contact angle β can be about 5° to about 7°, which is unacceptable. Thisis unacceptable because it results in an undesirable wetting effectacross substrate W and showerhead 612, based on a low surface tensionbetween these elements and immersion fluid 702. Wetting allows immersionfluid 702 to flow through gap 620, which is undesirable because theimmersion fluid is no longer contained.

FIG. 8 shows a contact angle α between an organic immersion fluid 702,having a higher index of refraction than water, with respect to ashowerhead 812, according to one embodiment of the present invention. Inone example, showerhead 812 is coated along a surface 830 in contactwith organic immersion fluid 702. In various example, the coatingcomprises a TEFLON like material, such as PTFE Poly-TetraFluorEthylene,TFE (TetraFluorEthylene), Teflon, CalF, or other a Teflon-likefluorinated hydrocarbon polymers. In another example, showerhead 812 canbe made from a TEFLON like material, rather than just coating surface830. It is to be appreciated that other materials that exhibit TEFLONlike characteristics could also be used.

Using a TEFLON coating on showerhead 812 or making showerhead 812 from aTEFLON material can increase contact angle α to be about 40° to about90°, which are highly desirable contact angles. With this increase incontact angle, a high surface tension is exerted on immersion fluid 702from showerhead 812, which substantially eliminates any flow ofimmersion fluid 702 through gap 620, e.g., allows for fluid containment.Thus, in a system using showerhead 812, last optic 604 can have a highnumerical aperture, e.g., about 1.11 to about 1.65 or above, and organicimmersion fluid can have a high index of refraction, e.g., 1.11-1.65 orabove, without wetting. This can result in a better resolution of apatterned beam being projected by projection system PL onto substrate W,yielding smaller and more accurate features formed on substrate W.

As discussed above, another problem can be corrosion of a showerhead 612when water is used as an immersion fluid 602. This corrosion can lead tocontamination of immersion fluid 602, which can reduce transmissioncharacteristics of immersion fluids. When short wavelengths of light areused, e.g., in a range of about 1 to 300 nm, this reduced transmissioncan result in undesirable patterns being formed on substrate W.

In one example, corrosion can be substantially reduced or eliminated byusing a glass-ceramic composite material, such as a Zerodur material, orthe like, for showerhead 612. This material is not as susceptible tocorrosion from water as steel. Thus, using Zerodur, or the like, forshowerhead 612 can substantially reduce or eliminate any contaminationof immersion fluid 602 caused by erosion of showerhead 612.

FIG. 9 shows a flowchart depicting a method 900, according to oneembodiment of the present invention. In step 902, a patterned beam ofradiation is projected onto a target portion of a substrate using aprojection system. In step 904, a liquid supply system is provided. Atleast a portion of the liquid supply system is one of coated with ormade from one of PTFE, TFE, Teflon, and a Teflon-like fluorinatedhydrocarbon polymer. In step 906, a space between the projection systemand the substrate is at least partially filled with an immersion liquidfrom the liquid supply system. Thus, wetness is reduced and containmentof the organic immersion liquid is maintained.

Although specific reference can be made in this text to the use oflithographic apparatus in the manufacture of ICs, it should beunderstood that the lithographic apparatus described herein can haveother applications, such as the manufacture of integrated opticalsystems, guidance and detection patterns for magnetic domain memories,flat-panel displays, liquid-crystal displays (LCDs), thin-film magneticheads, etc. The skilled artisan will appreciate that, in the context ofsuch alternative applications, any use of the terms “wafer” or “die”herein can be considered as synonymous with the more general terms“substrate” or “target portion,” respectively. The substrate referred toherein can be processed, before or after exposure, in for example atrack (a tool that typically applies a layer of resist to a substrateand develops the exposed resist), a metrology tool and/or an inspectiontool. Where applicable, the disclosure herein can be applied to such andother substrate processing tools. Further, the substrate can beprocessed more than once, for example in order to create a multi-layerIC, so that the term substrate used herein can also refer to a substratethat already contains multiple processed layers.

The terms “radiation” and “beam” used herein encompass all types ofelectromagnetic radiation, including ultraviolet (UV) radiation (e.g.,having a wavelength of or about 365, 248, 193, 157 or 126 nm).

The term “lens”, where the context allows, can refer to any one orcombination of various types of optical components, including refractiveand reflective optical components.

While specific embodiments of the invention have been described above,it will be appreciated that the invention can be practiced otherwisethan as described. For example, where applicable, the invention can takethe form of a computer program containing one or more sequences ofmachine-readable instructions describing a method as disclosed above, ora data storage medium (e.g., semiconductor memory, magnetic or opticaldisk) having such a computer program stored therein.

One or more embodiments of the invention can be applied to any immersionlithography apparatus, in particular, but not exclusively, those typesmentioned above and whether the immersion liquid is provided in the formof a bath or only on a localized surface area of the substrate. A liquidsupply system as contemplated herein should be broadly construed. Incertain embodiments, it can be a mechanism or combination of structuresthat provides a liquid to a space between the projection system and thesubstrate and/or substrate table. It can comprise a combination of oneor more structures, one or more liquid inlets, one or more gas inlets,one or more gas outlets, and/or one or more liquid outlets that provideliquid to the space. In an embodiment, a surface of the space can be aportion of the substrate and/or substrate table, or a surface of thespace can completely cover a surface of the substrate and/or substratetable, or the space can envelop the substrate and/or substrate table.The liquid supply system can optionally further include one or moreelements to control the position, quantity, quality, shape, flow rate orany other features of the liquid.

The immersion liquid used in the apparatus can have differentcompositions, according to the desired properties and the wavelength ofexposure radiation used. For an exposure wavelength of 193 nm, ultrapure water or water-based compositions can be used and for this reasonthe immersion liquid is sometimes referred to as water and water-relatedterms such as hydrophilic, hydrophobic, humidity, etc. can be used.

Although specific reference can be made in this text to the use oflithographic apparatus in the manufacture of a specific device (e.g., anintegrated circuit or a flat panel display), it should be understoodthat the lithographic apparatus described herein can have otherapplications. Applications include, but are not limited to, themanufacture of integrated circuits, integrated optical systems, guidanceand detection patterns for magnetic domain memories, flat-paneldisplays, liquid-crystal displays (LCDs), thin-film magnetic heads,micro-electromechanical devices (MEMS), etc. Also, for instance in aflat panel display, the present apparatus can be used to assist in thecreation of a variety of layers, e.g., a thin film transistor layerand/or a color filter layer.

While specific embodiments of the invention have been described above,it will be appreciated that the invention can be practiced otherwisethan as described. For example, the invention can take the form of acomputer program containing one or more sequences of machine-readableinstructions describing a method as disclosed above, or a data storagemedium (e.g., semiconductor memory, magnetic or optical disk) havingsuch a computer program stored therein.

Although specific reference can have been made above to the use ofembodiments of the invention in the context of optical lithography, itwill be appreciated that the invention can be used in otherapplications, for example imprint lithography, where the context allows,and is not limited to optical lithography. In imprint lithography atopography in a patterning device defines the pattern created on asubstrate. The topography of the patterning device can be pressed into alayer of resist supplied to the substrate whereupon the resist is curedby applying electromagnetic radiation, heat, pressure or a combinationthereof. The patterning device is moved out of the resist leaving apattern in it after the resist is cured.

CONCLUSION

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be apparent to persons skilledin the relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the invention.Thus, the breadth and scope of the present invention should not belimited by any of the above-described exemplary embodiments, but shouldbe defined only in accordance with the following claims and theirequivalents.

It is to be appreciated that the Detailed Description section, and notthe Summary and Abstract sections, is intended to be used to interpretthe claims. The Summary and Abstract sections can set forth one or more,but not all exemplary embodiments of the present invention ascontemplated by the inventor(s), and thus, are not intended to limit thepresent invention and the appended claims in any way.

1. A lithography system, comprising: an illumination system thatconditions a beam of radiation; a patterning device that patterns thebeam; a projection system that projects the patterned beam onto a targetportion of a substrate; and a liquid supply system that at leastpartially fills a space between the projection system and the substratewith an immersion liquid having an index of refraction greater than thatof water or about 1.10, wherein at least a portion of a surface of theliquid supply system is at least coated with PTFE, TFE, TEFLON, or aTeflon-like fluorinated hydrocarbon polymer.
 2. The lithography systemof claim 1, wherein the portion of the liquid supply system is ashowerhead.
 3. The lithography system of claim 1, wherein the portion ofthe liquid supply system is made from the PTFE, TFE, TEFLON, orTeflon-like fluorinated hydrocarbon polymer.
 4. The lithography systemof claim 1, wherein the immersion liquid has a contact angle of betweenabout 40° and about 90° with a surface of the substrate, a final portionof the projection system, or the liquid supply system.
 5. Thelithography system of claim 1, wherein the immersion liquid has acontact angle of about 60° with a surface of the substrate, a finalportion of the projection system, or the liquid supply system.
 6. Thelithography system of claim 1, wherein the immersion liquid has an indexof refraction of above 1.11.
 7. The lithography system of claim 1,wherein the immersion liquid has an index of refraction of about 1.65.8. The lithography system of claim 1, wherein the immersion liquid is anorganic fluid.
 9. The lithography system of claim 1, wherein theimmersion liquid is Decalin.
 10. The lithography system of claim 1,further comprising: a gas supply system that supplies gas that forms agas curtain around the immersion liquid at the surface of the substrate.11. The lithography system of claim 10, wherein the gas curtain protectsthe immersion liquid from oxygen.
 12. The lithography system of claim10, wherein the gas comprises nitrogen.
 13. The lithography system ofclaim 10, wherein the gas curtain is a knife edge gas curtain.
 14. Alithography system, comprising: an illumination system that conditions abeam of radiation; a patterning device that patterns the beam; aprojection system that projects the patterned beam onto a target portionof a substrate; and a liquid supply system that at least partially fillsa space between the projection system and the substrate with animmersion liquid, wherein the immersion liquid has an index ofrefraction greater than that of water or about 1.10.
 15. The lithographysystem of claim 14, wherein at least a portion of a surface of theliquid supply system is at least coated with PTFE, TFE, TEFLON, or aTeflon-like fluorinated hydrocarbon polymer.
 16. The lithography systemof claim 14, wherein the immersion liquid has an index of refraction ofabout 1.11 to about 1.65.
 17. The lithography system of claim 14,wherein the immersion liquid is Decalin.
 18. The lithography system ofclaim 14, wherein at least a portion the liquid supply system is madefrom the PTFE, TFE, TEFLON, or Teflon-like fluorinated hydrocarbonpolymer.
 19. The lithography system of claim 14, wherein the immersionliquid has a contact angle of between about 40° and about 90° with asurface of the substrate, a final portion of the projection system, orthe liquid supply system.
 20. The lithography system of claim 14,further comprising: a gas supply system that supplies nitrogen thatforms a knife-edge nitrogen barrier around the immersion liquid, wherebythe immersion liquid is protected from oxygen.
 21. A method, comprising:projecting a patterned beam of radiation onto a target portion of asubstrate using a projection system; using a liquid supply system, atleast a portion of which is coated with PTFE, TFE, TEFLON, or aTeflon-like fluorinated hydrocarbon polymer; and at least partiallyfilling a spaced between the projection system and the substrate with animmersion liquid having an index of refraction greater than that or wareor about 1.10 from the liquid supply system.
 22. A method, comprising:projecting a patterned beam of radiation onto a target portion of asubstrate using a projection system; providing a liquid supply system,at least a portion of which is made from PTFE, TFE, TEFLON, or aTeflon-like fluorinated hydrocarbon polymer; and at least partiallyfilling a spaced between the projection system and the substrate with animmersion liquid having an index of refraction greater than that ofwater or about 1.10 from the liquid supply system.